This invention relates generally to systems for grading fruit according to surface characteristics such as color and, more particularly, to systems that optically scan a succession of fruit moving along a conveyor.
Systems of this particular kind are now in general use in the fresh fruit industry, to grade the fruit according to certain color and blemish categories. The systems provide a significant cost savings over prior manual grading systems and also provide grading that is substantially more reliable and repeatable.
In typical grading systems of this kind, the fruit are moved successively past an array of cameras, which scan the fruit to detect the surface reflectivities of a large number of discrete segmental areas on the surface of each article of fruit. By comparing the reflectivity of each such segmental area with that of neighboring areas and by analyzing the color spectrum of the light received from each such area, the degree of blemish and the average color for each article of fruit can be ascertained.
Some of the grading systems of this kind have utilized just a single camera, with a conveyor that spins the fruit as they are moved past the camera. Such systems are not considered entirely effective, however, because to bring the entire surface of relatively large fruit into the camera's field of view requires a spin rate so high that the fruit can bounce on the conveyor and thereby prevent accurate grading. Thus, effective grading is generally considered to require multiple cameras.
Multiple-camera grading systems described briefly above have proven to be generally satisfactory in providing fairly accurate measures of surface blemishes and surface color for many kinds of fruit. However, the systems are believed to be in many ways unduly complex and are believed to be unduly limited in the kinds of blemishes and color variations that can be detected. There is a continuing need for simplified grading apparatus, and related method, that can grade fruit even more effectively into a wide variety of blemish and color categories. The present invention fulfills this need.